A substantial amount of the materials used for carpet underlay are produced from rebonded flexible organic foam and preferably rebonded polyurethane foam. Rebonded foam is generally obtained by a process which broadly consists of applying a binder to small particles of foam, compressing the resultant mix and allowing the binder to fully cure.
In manufacturing rebonded foam and particularly polyurethane foam, foam particles are placed in a suitable mixing container, such as a ribbon blender, where the foam particles are subjected to vigorous mixing. As the foam pieces are being agitated, a binder is sprayed into the mixing container. After the foam and binder are thoroughly blended, the mixture is transferred to a mold and compressed. The mixture is held in the compressed state until the resultant product is dimensionally stable. The resultant product may then be fabricated into whatever shape is required for the particular end use application.
The molding process generally produces a cylindrical roll or log of rebonded polyurethane foam.
These rolls or logs are then cut into sheet material. The molding procedures generally known in the art suffer many disadvantages common to batch operations including high cost and relatively low production costs. Additionally, significant problems are generally encountered relative to product characteristics such as uniformity of density, scrap loss, and reproducibility.
One process available commercially consists broadly of the following steps: filling a mold with a mixture of foam and binder, compressing the mixture, curing the binder while the mixture is in the compressed state, drilling a hole in the cured product and removing the mold from the product. Since so much of this process is dependent on human factors, one serious problem was the relatively low yields obtained since the process is directly dependent on how fast the human worker could move the mold from station to station.
Substantially all the problems noted above were solved by the invention described in U.S. Pat. Nos. 4,243,617 and 4,243,625, and the disclosures of which are herein incorporated by reference. While the inventions described in the above-noted patents substantially increased the production rate for rebonded foam, they also created a bottleneck in the overall production of foam sheets. More particularly, although rebonded foam cylinders were produced at a high rate, the subsequent peeling operation was still essentially a labor intensive operation with the end result that a substantial amount of rebonded foam had to be stored to await subsequent peeling.
Although peeling equipment has been described (see, e.g., U.S. Pat. Nos. 3,874,988 and 3,223,568), and is commercially available from companies such as Edge Saw Manufacturing Co. (see brochure No. E.S. S-30-72) and Fecken-Kirfel KG--Engineering and Machine Co. (see brochure entitled "Bandknife Peeling Machines"), there is not presently available a complete operation for the substantially continuous production of foam in sheet form from a cylindrical roll or log. The present invention fills this need .